Anatomy of the Respiratory System: Trachea and Bronchi

Overview

• The respiratory system includes:
  • Nose and nasal cavity
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Lungs

Anatomy of the Trachea

• Also known as the windpipe.
• Directs air to/from the lungs.
• Length: 9-15 cm; Diameter: 2-2.5 cm.
• Extends from C6-C7 to T4-T5 vertebrae.

Structure

• Tracheal Cartilages: Horseshoe-shaped; support smooth airflow.
• Annular Ligaments: Connect adjacent cartilages.
• Membranous Part: Dorsal fibromuscular membrane.

Tracheal Wall Layers

1. Tunica Mucosa
   • Contains lymphoid nodules and tracheal glands.
   • Protects against microorganisms.
2. Tela Submucosa
   • Loose connective tissue and blood vessels.
3. Tracheal Cartilages & Membranous Part
4. Tunica Adventitia
   • Dense connective tissue for protection.

• Carina of Trachea: Ridge of last cartilage before bifurcation.

Anatomy of the Bronchi

• Primary Bronchi: Right (shorter, wider, more vertical) and Left (longer, narrower, more curved).
  • Right bronchus: Prone to foreign body aspiration.
• Hilum of the Lung: Entry point for bronchi.

Bronchial Tree

• Lobar Bronchi:
  • Right: 3 lobes (Superior, Middle, Inferior)
  • Left: 2 lobes (Superior, Inferior)
• Segmental Bronchi:
  • Right: 10 segments
  • Left: 8 segments
• Terminal Bronchioles: 0.5-1 mm diameter, end of bronchial tree.

Function

• Air conduction and protection.
• Ciliated respiratory epithelium traps irritants.

Alveolar Tree

• Alveoli: Primary site for gas exchange.
• Bronchioles: Transition to alveolar tree.
  • Alveolar Ducts: Lead to alveolar sacs.
  • Highly vascularized for efficient gas exchange.

Layers Comparison: Tracheal, Bronchial, and Bronchiolar Walls

• Trachea:
  • Tunica Mucosa (respiratory epithelium) , Tela Submucosa, Tracheal Cartilage, Smooth muscle ( membranous part), Tunica Adventitia.
• Bronchus:
  • Tunica mucosa (respiratory epithelium) , Tela submucosa (loose connective tissue) , FibroMusculoCartilaginous Layer (blending of muscle, cartilage, and fibrous layers).
• Bronchiole:
  • Tunica mucosa (Inner cuboidal/simple squamous epithelium), Tela Submucosa, smooth muscle layer (Tunica Muscularis), Tunica Adventitia.

Conclusion

• Covered the anatomy of the trachea and bronchi.
• Next video topic: Lungs.